Feline Behaviorist Pam Johnson-Bennett is the author of a number of award-winning and critically acclaimed books, including Think Like a Cat and Psycho Kitty. The innovative methods described in all her books are based on Pam's unique way of training by actually understanding the way a cat thinks. She makes numerous television appearances including CNN, Fox News Channel, and National Geographic specials, as well as being a popular guest on many nationally syndicated radio programs. She is now considered to be one of the leading experts on feline behavior.

Q: We have a male cat who is about 10 months old. We let him play in the backyard, and recently a big black cat started coming to our yard every night around 7pm. I saw them murmur to each other and sometimes I observed that our little cat's tail becomes big and thick when he is with this other cat. The strange thing is when we try to get the black cat to leave, the black cat becomes defensive and won't leave, even if we try to scare him away. The black cat is very firm and even makes fighting sounds when we try to get him to leave. What should we do? We really care about our cat and we want him to have playmates, but we also don't want him to be threatened by other cats. How can we tell if our cat is OK?

A: Your kitty's behavior is very normal. A cat is naturally territorial and the appearance of an unfamiliar cat in "his territory" can be very threatening. Your cat's body language (puffing up his tail), plus the aggressive behavior of the other cat are indications that the encounter between the two of them isn't friendly. This black cat is not a playmate. Your young cat is at risk of getting injured if the two of them fight. You also don't know the health status of this cat, so to be safe it's best to keep your cat indoors and away from other outdoor cats.

If you want a playmate for your kitty, consider getting a second cat. After a gradual introduction so the two can get to know each other, they'll very likely become friends.